This invention relates to an improved tool, such as scissors, shears and the like, and to an improved method for making such an improved tool.
From the first, scissors, shears and like tools have included two cooperating members that are innerconnected, by a pivot pin, bolt and nut, rivet, screw or the like, at a connection point located between their ends, so that the members can be moved, with "scissors-like" action, between a closed position and an open position. Each of the members commonly have a handle formed at their one end, a shank portion disposed between the handle and the connection point, i.e., the pivot pin, bolt and nut, rivet, screw, etc., and a blade portion disposed between the connection point in their other end. The blade portions and the shank portions each have an inside face and an outside face. The blade portions also include cutting edges which usually extend from adjacent to the connection point to their other ends. The members are generally arranged so that when they are in their closed position, the two inside faces of the blade portions and the two inside faces of the shank portions at least partially overlap and are adjacent to each other.
For many years, the manufacture of scissors, shears and like tools, and especially high quality tools, has required a significant amount of skilled hand work and particularly hand grinding operations. These hand grinding operations include the shaping and sharpening of the inside and outside faces and the cutting edges.
One of the most critical and time consuming of these hand grinding operations was the grinding of the surface or the "ride" of the inside faces of the shank portions so that when these inside faces are moved into contact with each other, as when the members are moved from their open to their closed position, the blade portions will be biased together so as to provide a satisfactory cutting or shearing action. When the hand grinding operation has been properly done, there only will be a "point contact" or "point of contact" between the cutting edges of the members. The artisans doing this critical hand grinding operation always attempt to grind the inside faces of the shank portions so that this point contact between the cutting edges is initially located near the point of initial intersection between the cutting edges and then moves out, along the cutting edges, to their other distal ends as the members are moved to their closed position. Ideally, this critical hand grinding operation should also impart a desirable "feel" to the tool, i.e., require a constant force to move the members from their open position to their closed position.
It has long been recognized by those skilled in this art that the hand grinding of the inside faces of the shank portions by skilled artisans was one of the most time consuming and thus expensive operations involved in the manufacture of scissors, shears and like tools. Nevertheless, the art has continued to utilize such a hand grinding operation. This is not to say, however, that others in the art have not suggested tools or methods of manufacture which do not require this critical hand grinding operation. For example, the Conover U.S. Pat. No. 222,672; the Wheeler U.S. Pat. No. 565,193; the Chapin U.S. Pat. No. 947,626; the Ladd U.S. Pat. No. 865,918; the Wertepny et al U.S. Pat. No. 2,600,236; the Rothstein U.S. Pat. No. 2,828,541; and the Sommervell et al U.S. Pat. No. 3,460,251 disclosed structure that was apparently intended to overcome this long standing problem in the art. However, as noted above, the art has continued to rely on the expertise of skilled artisans to perform the critical hand grinding of the inside faces of the shank portions of the members of the tools.
One of the principal objects of my present invention is to provide an improved, high quality tool, such as scissors, shears or the like, which does not require any significant hand grinding of the inside faces of the shank portions of the members in order to achieve point contact between the cutting edges of the members and which accordingly can be manufactured at a relatively low cost, as compared to tools and manufactured utilizing the heretofore conventional hand grinding operation. Another principal object of my present invention is to provide an improved method of manufacturing an improved tool, such as a scissors, shears or the like, wherein a simple punching operation is utilized, instead of the critical hand grinding operation that was heretofore required, in order to obtain a satisfactory high quality tool.
More specifically, the improved tool of my present invention includes first and second cooperating members. Each of these members have a handle on their one ends and are interconnected, at a connection point located intermediate their ends, by a screw, pivot pin, rivet or the like, so that the members may pivotally move about the connection point between an open position wherein the two handles and the other ends of the members are spaced apart and a closed position wherein the two handles are adjacent to each other and the other ends of the members are adjacent to each other. Shank portions are disposed on each of the first and second members between their handles and the connection point, and each shank portion includes an outside face and inside face. Blade portions are disposed on each of the first and second members between the connection point and the other ends of the members and each includes an inside face, an outside face, and a cutting edge that extends from adjacent to the connection point to the other end of the member. The members are constructed and arranged so that as the members are moved from their open position to their closed position, the inside faces of the shank portions overlie or overlap each other and are adjacent to each other.
A novel bearing dimple is formed in the inside surface of one of the shank portions by using a conventional punch tool to punch the outside face of the shank portion. This bearing dimple projects above and from the surface of the inside face of the one shank portion and is adapted to contact the inside face of the other shank portion as the first and second members are moved from their open position to their closed position. The contact between the bearing dimple and the inside face of the other shank portion biases or "tilts" the one ends of the members apart, about the connection point, so that there will be "point contact" between the cutting edges of the first and second members. The bearing dimple is disposed, vis-a-vis, the connection point so that the initial "point contact" or "point of contact" between the cutting edges is adjacent the connection point as the cutting edges first intersect during the movement of the first and second members from their open position to their closed positions. This "point of contact" then moves out along the cutting edges to the other ends of the members as the first and second members continue to be moved to their closed positions. In practice, it has been found that especially satisfactory cutting or shearing results can be obtained when the distance between the bearing dimple and the connection point is at least equal to the distance between the connection point and the cutting edge.
As noted above, the utilization of a bearing dimple, instead of the heretofore required hand grinding operations on the inside faces of the shank portions, significantly reduces the time and cost of manufacturing a scissors, shears or other like tools without any impairment of the quality of the finished tool. In addition, my present invention affords another important advantage, from the standpoint of marketing my improved tool, since the invention enables all tools made utilizing such a bearing dimple to have the same "feel", viz., the same force is required to move the tools from their open to their closed positions. In contrast, tools made by the heretofore conventional hand grinding operation each had an individual "feel" since even a skilled artisan has difficulty grinding two separate tools exactly the same way.
The utilization of the novel bearing dimple of my present invention affords still another important advantage. One of the finishing steps in the manufacture of scissors, shears and like tools is the manual "setting" of the blades, i.e., bending the blades so that the cutting edges will properly meet. Again the uniformity of the height of the bearing dimples permits this "setting" operation to be done relatively quickly and easily and, of course, such minimumization of hand labor reduces the cost of manufacture.
In summary then, tools embodying my novel bearing dimple can be manufactured at a significantly lower cost since there is a marked savings in the time and manual labor required for manufacturing the tools. In addition, relatively unskilled laborers can be used to perform many of the manufacturing operations which heretofore required skilled, experienced artisans. Furthermore, improved tools of my present invention have an uniform "feel" which is a real advantage when the tools are utilized for industrial production work. Thus, my invention represents a significant breakthrough in this art and affords a practical solution to a long standing problem in the art.
These and other objects and advantages to my present invention will become apparent from the following description of the preferred embodiment of my invention, described in connection with the accompanying drawings.